#include "pch.h"
#include <iostream>

using namespace std;

class Solution {
public:
	int climbStairs(int n) {
		if (n == 1)
			return 1;
		else if (n == 2)
			return 2;
		else
			return climbStairs(n - 1) + climbStairs(n - 2);
	}
};

int main()
{
	Solution s;
	int num = 20;
	int res = s.climbStairs(num);
	cout << res << endl;

	return 0;
}